The overall goal of this K23 proposal is to train Matthew J. O'Brien, MD, MSc for a career as an independent investigator in obesity and diabetes prevention, with a specific focus on Latinas-a demographic group at high risk for these related disorders. While there have been attempts to translate the evidence-based Diabetes Prevention Program (DPP) into community settings, very few of these studies have included Latinas. Community health workers, or promotoras, are trained lay people who provide health education, and could serve as leaders of weight loss and diabetes prevention efforts in Latinas. Previous research has demonstrated that promotoras are an effective lay health workforce, but no published studies have applied this intervention model to diabetes prevention in Latinas. Dr. O'Brien plans to address this gap in knowledge by developing a promotora-led lifestyle intervention (PLI), informed by the DPP, to promote weight loss and reduce cardiometabolic risk in Latinas. There are 3 Phases to the proposed research that will address corresponding specific aims: Phase 1 uses focus groups to explore the social and cultural context surrounding weight-related behaviors in Latinas at-risk for diabetes, applying the findings to develop PLI; Phase 2 involves piloting PLI in a single-arm trial, and assessing its feasibility and acceptabilit; Phase 3 will test the effects of PLI on changing at-risk Latinas' weight and cardiometabolic markers in a randomized controlled trial. In order to successfully complete the proposed research plan, Dr. O'Brien will receive additional training through formal coursework and structured mentorship in the following 3 areas: 1) qualitative methods; 2) randomized controlled trials for weight loss and diabetes prevention; and 3) foundations in obesity, diabetes, and metabolism. Temple University is home to internationally-recognized researchers in each of these areas of study, who will serve as Dr. O'Brien's mentors. The site for the proposed research is a community health center founded by Dr. O'Brien-Puentes de Salud (Bridges of Health)-which serves a Latino population and has been the site of several promotora-based studies involving the target population since 2007.